Immune system is an important aspect in our body and plays a vital role . It protects the body from harmful and toxic substances . Any entry of foreign substance in the body is called antigens . Antigen can be any virus , microbes or any bacteria and when the body encounters any of the antigens. Some of the cells such as white blood cells secretes antibodies against these microbes. The immune system helps to fight against germs and foreign substances on the skin ,in the tissues of the body and in bodily fluids such as bloods. The immune system is made up of two parts: the innate immunity and the adaptive immune system .These two systems works closely together on different tasks